<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="js/vue.js"></script>
    <title>Document</title>
</head>
    <body>
        <div id="app">
           <div v-if="isShow" ref=""self>
                test
            </div>
            <button @click="isShow=!isShow">更新</button>
        </div>
        <script>
            var vm = new Vue({
                el:"#app",
                data:{ 
                    isShow:false
                },
                beforeUpdate() {
                    console.log('更新之前')
                    console.log(this.$refs.self)//通过this.$el获取el的DOM元素
                },
                updated() {
                    console.log('更新之后')
                    console.log(this.$refs.self)
                }
            })
         </script>
    </body>
</html>